The present invention relates to fluid flow machines in general, and more particularly to improvements in motor-pump aggregates wherein the pump is a diaphragm pump which can be used to advance metered quantities of a liquid, gas or otherwise flowable medium. Still more particularly, the invention relates to improvements in fluid flow machines wherein the diaphragm of the diaphragm pump can be deformed by a motor which can constitute or include an electromagnet and wherein one or more movable parts (e.g., actuating or adjusting devices) extend from the enclosure for the pump and its motor.
It is already known to construct a fluid flow machine of the above outlined character in such a way that the pump head is disposed at one axial end of the enclosure, that the diaphragm in the pump head is deformable by the reciprocable armature of an electromagnet in cooperation with a coil spring or another suitable resilient element, and that the enclosure further contains a control unit which generates and transmits impulses for energization of the electromagnet. A fluid flow machine which embodies a diaphragm pump and is constructed in the above outlined manner is disclosed, for example, in German Pat. No. 23 22 764. The patented machine exhibits the advantage that all essential components (including the pump, the electromagnet and the control unit) are confined in a common enclosure and thus constitute a unitary structure. This contributes to compactness of the machine and facilitates the installation. However, the patented machine also exhibits serious drawbacks, especially that it cannot be set up in an explosive atmosphere because the generation of a single spark or overheating of the electromagnet is likely to touch off a fire, an explosion or a series of explosions in the area around the enclosure for such machine. A spark can develop in that portion of the enclosure which accommodates the electromagnet and/or in the portion which confines the control unit. The possibility of spark generation in certain portions of the structure which is installed in the enclosure of the patented machine cannot be excluded; therefore, such machines are not suited for transport of flammable media and/or for use in areas which contain or are likely to contain explosive or flammable substances. This greatly reduces the usefulness and versatility of the patented machine.
Certain known electromagnetically operated diaphragm pumps are designed with a view to ensure that the electromagnets meet the requirements for "increased safety" in areas containing explosive and/or flammable substances. Reference may be had to the pamphlet No. D-1-400d which describes so-called LEWA metering pumps. The electromagnets of the motors for such pumps are immersed in oil, and the control unit is installed in a separate casing which can be set up at a locus remote from the danger area, namely, far away from the area which is likely to contain explosive or flammable substances. Such solution is cumbersome and expensive, and the installation takes up much time because the casing for the control unit must be mounted independently of the aggregate including the diaphragm pump and its motor.